1. Field of the Invention
The present invention relates to a deodorizing and sterilizing apparatus using ozone and chlorine dioxide.
2. Description of the Prior Art
Japanese Patent Publication No. 58-25437 discloses a deodorizing and sterilizing method using ozone in which ozone is introduced at a concentration exceeding 100 ppm so as to sterilize and decompose biohazard factors and, thereafter, residual ozone is removed by activated carbon.
According to this method, surface sterilization requires sterilization conditions including an ozone concentration of 200 ppm, a humidity exceeding 90%, and a treatment time of more than 4 hours (according to an article entitled "Fundamental Study on Effectiveness of Ozone Fumigation Disinfection in the Region of Laboratory Animals", August, 1989). This means that the ozone sterilization must be carried out at a very high humidity level exceeding 90%.
Another deodorizing and sterilizing method using ozone is disclosed in Japanese Patent Publication No. 63-59705 in which ozone is added at a concentration of 10 to 5000 ppm and decomposed by being subjected to a catalytic and discharge reaction. This method also requires a very high humidity level exceeding 90% when applied to a surface sterilization of bacteria.
Japanese Patent Publication No. 63-108137 discloses a deodorizing and sterilizing method by using chlorine dioxide adsorbed on a porous material. This method also needs a humidity exceeding 99% as an indispensable condition. As in the case of the foregoing deodorizing and sterilizing methods using ozone, this method using chlorine dioxide has a problem that a very high humidity level is needed.
Another drawback associated with the ozone deodorization and sterilization method is a relatively low permeability to an object to be sterilized. For instance, the permeability to a powdery material such as flour is only about 1 mm. The chlorine dioxide deodorization and sterilization method excels in permeability. However, due to a complicated oxidation mechanism, its sterilizing or bactericidal power is relatively low.
In addition, since the adsorbent and the catalyst have a porous surface structure including a multiplicity of pores of a diameter ranging from several .mu. to several .ANG., when they are used under conditions in which relative humidity exceeds 80%, all the pores are fulled with water molecules. As a consequence, the adsorbability of the adsorbent and the catalytic effect of the catalyst are considerably lowered.